Silicon carbide (SiC) is expected as a material for a next-generation semiconductor device. The bandgap of SiC is three times wider than that of silicon (Si), the breakdown field strength thereof is about ten times higher than that of Si, and the thermal conductivity thereof is about three times higher than that of Si. The use of these characteristics makes it possible to achieve a semiconductor device which has low power loss and can operate at a high temperature.
When a surge voltage is applied between electrodes of a metal oxide semiconductor field effect transistor (MOSFET), avalanche breakdown occurs. For example, when the avalanche breakdown occurs at a region, which is unexpected in device design, other than a cell region, there is a concern that the device will be broken.
SiC has characteristics that, for example, the sheet resistance of a p-type impurity region or contact resistance with the p-type impurity region is high, as compared to Si. A device needs to be designed considering the characteristics of SiC in order to improve the avalanche tolerance of the device.